arch/arm/kernel/psci_smp.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *
   4  * Copyright (C) 2012 ARM Limited
   5  *
   6  * Author: Will Deacon <will.deacon@arm.com>
   7  */
   8
   9 #include <linux/init.h>
  10 #include <linux/smp.h>
  11 #include <linux/of.h>
  12 #include <linux/delay.h>
  13 #include <linux/psci.h>
  14
  15 #include <uapi/linux/psci.h>
  16
  17 #include <asm/psci.h>
  18 #include <asm/smp_plat.h>
  19
  20 /*
  21  * psci_smp assumes that the following is true about PSCI:
  22  *
  23  * cpu_suspend   Suspend the execution on a CPU
  24  * @state        we don't currently describe affinity levels, so just pass 0.
  25  * @entry_point  the first instruction to be executed on return
  26  * returns 0  success, < 0 on failure
  27  *
  28  * cpu_off       Power down a CPU
  29  * @state        we don't currently describe affinity levels, so just pass 0.
  30  * no return on successful call
  31  *
  32  * cpu_on        Power up a CPU
  33  * @cpuid        cpuid of target CPU, as from MPIDR
  34  * @entry_point  the first instruction to be executed on return
  35  * returns 0  success, < 0 on failure
  36  *
  37  * migrate       Migrate the context to a different CPU
  38  * @cpuid        cpuid of target CPU, as from MPIDR
  39  * returns 0  success, < 0 on failure
  40  *
  41  */
  42
  43 extern void secondary_startup(void);
  44
  45 static int psci_boot_secondary(unsigned int cpu, struct task_struct *idle)
  46 {
  47         if (psci_ops.cpu_on)
  48                 return psci_ops.cpu_on(cpu_logical_map(cpu),
  49                                         virt_to_idmap(&secondary_startup));
  50         return -ENODEV;
  51 }
  52
  53 #ifdef CONFIG_HOTPLUG_CPU
  54 static int psci_cpu_disable(unsigned int cpu)
  55 {
  56         /* Fail early if we don't have CPU_OFF support */
  57         if (!psci_ops.cpu_off)
  58                 return -EOPNOTSUPP;
  59
  60         /* Trusted OS will deny CPU_OFF */
  61         if (psci_tos_resident_on(cpu))
  62                 return -EPERM;
  63
  64         return 0;
  65 }
  66
  67 static void psci_cpu_die(unsigned int cpu)
  68 {
  69         u32 state = PSCI_POWER_STATE_TYPE_POWER_DOWN <<
  70                     PSCI_0_2_POWER_STATE_TYPE_SHIFT;
  71
  72         if (psci_ops.cpu_off)
  73                 psci_ops.cpu_off(state);
  74
  75         /* We should never return */
  76         panic("psci: cpu %d failed to shutdown\n", cpu);
  77 }
  78
  79 static int psci_cpu_kill(unsigned int cpu)
  80 {
  81         int err, i;
  82
  83         if (!psci_ops.affinity_info)
  84                 return 1;
  85         /*
  86          * cpu_kill could race with cpu_die and we can
  87          * potentially end up declaring this cpu undead
  88          * while it is dying. So, try again a few times.
  89          */
  90
  91         for (i = 0; i < 10; i++) {
  92                 err = psci_ops.affinity_info(cpu_logical_map(cpu), 0);
  93                 if (err == PSCI_0_2_AFFINITY_LEVEL_OFF) {
  94                         pr_info("CPU%d killed.\n", cpu);
  95                         return 1;
  96                 }
  97
  98                 msleep(10);
  99                 pr_info("Retrying again to check for CPU kill\n");
 100         }
 101
 102         pr_warn("CPU%d may not have shut down cleanly (AFFINITY_INFO reports %d)\n",
 103                         cpu, err);
 104         /* Make platform_cpu_kill() fail. */
 105         return 0;
 106 }
 107
 108 #endif
 109
 110 bool __init psci_smp_available(void)
 111 {
 112         /* is cpu_on available at least? */
 113         return (psci_ops.cpu_on != NULL);
 114 }
 115
 116 const struct smp_operations psci_smp_ops __initconst = {
 117         .smp_boot_secondary     = psci_boot_secondary,
 118 #ifdef CONFIG_HOTPLUG_CPU
 119         .cpu_disable            = psci_cpu_disable,
 120         .cpu_die                = psci_cpu_die,
 121         .cpu_kill               = psci_cpu_kill,
 122 #endif
 123 };